Natalie Portman, best actress nominee for her role in "Black Swan", and her fiance, Benjamin Millepied arrive at the 83rd Academy Awards in Hollywood, California, February 27, 2011. Portman is dressed by Rodarte.

Natalie Portman and her fiancé Benjamin Millepied, who is also her co-star in the 2010 film “Black Swan,” joined over 100,000 people in a signature petition to President Barack Obama in support of gay marriage.

Portman, who won an Academy Award this year for her performance in “Black Swan,” which includes a lesbian sex scene, joins other celebrities in urging President Obama to “take the next step” and allow gay and lesbian couples to legally marry.

As of Thursday morning, about 98,000 people have shared Freedom to Marry’s “I Do” open letter to Obama. And the letter has 110,125 signers to date.

“Natalie Portman and her fiancé, Benjamin Millepied, are in love, and believe all loving couples should be able to share in the freedom to marry without discrimination,” said Evan Wolfsen, president of Freedom to Marry, in a statement this week.

The issues of homosexuality and gay marriage have increasingly divided Christians in recent years, with younger evangelicals being more open to legal recognition of gay couples than older generations. Although young white evangelicals are more pro-life than their predecessor, on the issue of same-sex marriage they are more than twice as likely than the overall white evangelical population to support gay marriage (24 percent to 10 percent), according to a Third Way and Public Religion Research report last year.

Overall, a majority (52 percent) of young white evangelicals support either civil union (28 percent) or marriage between people of the same sex, according to the report.

Focus on the Family President Jim Daly noted in an interview last month with World Magazine that people in their 20s and 30s are especially likely to support same-sex marriage.

“We’re losing on that one, especially among the 20- and 30-somethings: 65 to 70 percent of them favor same-sex marriage,” said Daly about how evangelicals are doing in their efforts to support traditional marriage. “I don’t know if that’s going to change with a little more age – demographers would say probably not.

“We’ve probably lost that. I don’t want to be an extremist here, but I think we need to start calculating where we are in the culture.”

But Daly called on Christians to defend marriage “as best as we can” and make sure believers’ marriage are healthy to be “a good witness to the world.”

In a recent interview with Reformed theologian John Piper, influential Pastor Rick Warren spoke about his clear stance on homosexuality while in the media spotlight.

“Larry King has asked me very pointedly, for instance, about homosexuality two or three times and I made no bones about it,” said Warren in the video posted on the Desiring God website. “And I said, Larry, let’s don’t even argue this from Scripture. I said, take a human body, a male and a female, it is obvious that certain parts are meant together. There is a purpose and a design for it and there is a result of that. I rest my case.”

In addition to urging President Obama to legalize same-sex marriage at a federal level, the signers of Freedom to Marry’s “I Do” letter also thanked him for ordering the Justice Department in February to stop defending the constitutionality of the Defense of Marriage Act – the 15-year-old federal law that defines marriage as between a man and woman.

“Mr. President, marriage matters. In law, in love, in life, marriage says ‘we are family’ in a way that nothing else does,” reads Freedom to Marry’s “I Do” letter. “And marriage brings not only public respect and personal significance, but also a safety net of legal protections, rights, and responsibilities for which there is no substitute.

“We ask you now for your leadership on ending the exclusion of same-sex couples from marriage … You can put government on the side of those seeking to care for their loved ones, instead of those standing in their way.”

In February, the Department of Justice announced that it would discontinue asserting the Defense of Marriage Act’s constitutionality in federal court. Christians and conservatives argue that Obama is disregarding his duty to defend federal law.

Republican House Speaker John Boehner has, in response, vowed to defend DOMA in court. He said the decision to step in was “necessitated by the extraordinary announcement” by the DOJ to stop defending DOMA and the House taking action ensures that the courts will decide the constitutionality of the marriage law.